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If your study forced the respondent to report ranges (e.g., 1-5, 6-10, 11-15, 16-20, etc.) please simply use the midpoint of the range. For example, if one range is 1-5 DPW, we assume they drink 2.5 DPW on average. Then use these midpoints in all subsequent analysis.
If your study forced the respondent to report ranges (e.g., 1-5, 6-10, 11-15, 16-20, etc.) please simply use the midpoint of the range. For example, if one range is 1-5 DPW, we assume they drink 2.5 DPW on average. Then use these midpoints in all subsequent analysis.
== Covariate Correction ==
== Covariate Correction (left-anchor and log tranformation)==
For CPD we will consider the binned responses to be on an ordinal scale.
For CPD we will consider the binned responses to be on a quantitative scale from 1-4 (see above under the CPD phenotype description). CPD therefore '''will not''' require transformation prior to covariate correction.
For all other phenotypes (Pack Years, Smoking Initiation, Age of Initiation, Drinks Per Week) please '''left-anchor''' the distribution at 1 and '''log-transform it'''. (Left-anchoring, such that no value is less than 1, prevents the log-transform from returning nonsensical values like negative infinity).
Appropriate covariates can often be study-specific. We will depend on local investigators to determine the most appropriate covariates. We list here some covariates that will likely be necessary.
Appropriate covariates can often be study-specific. We will depend on local investigators to determine the most appropriate covariates. We list here some covariates that will likely be necessary.
=== Main Effects ===
=== Main Effects ===
*Age
*Age
**At assessment for current smokers/drinkers
**At assessment in current smokers/drinkers
**Age of smoking/drinking for former smokers/drinkers could be age at quitting
**Age of smoking/drinking for former smokers/drinkers could be age at quitting
**At assessment for Pack Years, Smoking Initiation, and Age of Initiation, regardless of current/former smoking status
**At assessment for Pack Years, Smoking Initiation, and Age of Initiation, regardless of current/former smoking status
*Age^2
*Sex
*Sex
*Date of birth (or year, or range)
*Date of birth (or year, or range)
